1. Field of the Invention
The present invention relates to fluoropolymers and, in particular, relates to fluoropolymer coatings, such as coatings of the type used on rigid substrates such as cookware or other applications in which a non-stick surface and/or abrasion resistant surface is desired. In particular, the present invention relates to a fluoropolymer coating having improved non-stick or release characteristics and/or improved abrasion resistance.
2. Description of the Related Art
Fluoropolymers are long-chain polymers comprising mainly ethylenic linear repeating units in which some or all of the hydrogen atoms are replaced with fluorine. Examples include polytetrafluoroethylene (PTFE), methylfluoroalkoxy (MFA), fluoro ethylene propylene (FEP), perfluoroalkoxy (PFA), poly(chlorotrifluoroethylene) and poly(vinylfluoride).
Non-stick coating systems including fluoropolymers are applied in single or multiple coats to the surface of a substrate to provide a coated substrate having a non-stick coating to which extraneous materials will not adhere. In a multiple layer coating system, the non-stick coating generally includes a primer and a topcoat, and optionally, one or more midcoats.
The use of non-stick coating systems which are applied to a substrate in multiple layers has been known for many years. The primers for such systems typically contain a heat resistant organic binder resin and one or more fluoropolymer resins, along with various opaque pigments and fillers. The midcoats contain mainly fluoropolymers with some amounts of opaque pigments, fillers and coalescing aids, while the topcoats are almost entirely composed of fluoropolymers, such as entirely high molecular weight polytetrafluoroethylene (HPTFE), or HPTFE with a small amount of a melt-processible fluoropolymer.
What is needed is a non-stick coating system that is an improvement over the foregoing.